1. Technical Field
The present invention relates generally to nutrition and more particularly to a method and nutritional composition for improving glucose and insulin balance in an individual. In one embodiment, the invention provides a nutritional composition having a carbohydrate:fat:protein ratio of about 1:1:1, useful in the treatment of a disease or condition associated with diabetes, such as cardiovascular disease or metabolic syndrome.
2. Related Art
Obesity and Type 2 diabetes mellitus incidence in the US has increased dramatically in the past 3 decades, and especially the past decade. Incidence of Type 2 diabetes, and co-morbidities, such as cardiovascular disease, has increased in direct relation to obesity. The epidemic of these chronic diseases has led to an emphasis on dietary management of obesity and insulin resistance. Intentional weight loss markedly reduces the risk of Type 2 diabetes mellitus and cardiovascular risks. Alternative diets such as “Atkins” or “Ornish” have become increasingly popular over the last couple of decades. These diets focus on extremes of fat or carbohydrate (high fat or high carbohydrate diets).
A very low carbohydrate diet, such as Atkins, is currently popular as a weight loss diet. However, there is no consensus on the levels of carbohydrates, protein and fat in the diet that is optimal for weight management and insulin sensitivity. Few recent studies suggest that high fat/high protein ketogenic diets favor significant weight loss. But, it is not clear whether high protein or high fat or low carbohydrate, or a combination of these factors, in these diets are responsible for the observed metabolic effects. Thus, the effect of macronutrient composition of diet on adiposity and insulin resistance is still unclear.
Macronutrient balance may be a critical factor. High fat diets generally, according to current literature, induced obesity and adiposity in males and females. High-fat diets and high-carbohydrate ad lib diets in females have been shown to impair insulin sensitivity. Also, high carbohydrate diets markedly elevate liver weights, liver triglycerides and liver esterified cholesterol (EC).
Human studies have reported more weight loss with low carbohydrate diets compared to low fat diets. The low carbohydrate diets included foods high in fat and protein resulting in high fat/high protein content. This suggests that the ratio of dietary fat to protein may be a critical factor in regulating energy balance, adipose mass and weight gain. High carbohydrate diets result in the lowest weight gain when caloric intake was restricted to that of high fat/high protein diet. Glucose metabolism and oxidation has been found to be more efficiently up-regulated according to dietary carbohydrate intake. However, high carbohydrate diets have been reported to increase hepatic lipogenesis and reduce fatty acid oxidation and lipolysis, leading to weight gain, likely due to excess caloric intake as carbohydrate.
National Health and Nutrition Examination Survey (NHANES; 1988-94) and Carbohydrate Intake On Obesity (Yang et al. 2003, AJCN 77: 1426) in FIGS. 1-2 shows that high-carbohydrate intake leads to lower insulin secretion. This is accomplished without significant change in the levels of HbA1c, fasting serum glucose, and insulin. This has been interpreted in the literature as insulin is more efficient as carbohydrate increases.
Further, Yang shows that high-fat+high-protein intake leads to higher energy intake, greater BMI, and greater insulin secretion with main shifts occurring at approximately >30% fat (negative impact) and >15% protein (positive impact).
Dansinger, M. et al (JAMA 2005; 293:45-53) compared Atkins Diet (low carbohydrate), Zone Diet (30:30:40 ratio of calories from proteins, fats and carbohydrates), Weight Watchers (low calories, low fat diet) and Ornish (high carbohydrate, low fat). The results showed that at 12 weeks, Ornish, Zone and Weight Watchers all had greater weight loss than Atkins (FIG. 3).
A sample Atkins and Ornish ratio is illustrated in FIG. 4. FIGS. 5-6 illustrate the effect of these diets on weight gain in Diet Induced Obesity (DIO) mice and insulin tolerance on male ApoE-mice.